Problems assciated with the operating reliability of heavy-duty hydraulic turbines
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The study and codification of the operating experience gained with heavy-duty rotary-blade and radial-axial hydraulic turbines made it possible to obtain quantitative estimates of the reliability characteristics of basis subassemblies and components of the equipment and to ascertain the character of the failure distribution as a function of turbine operation. The estimates obtained make it possible to make a positive comparison and selection of the structural utility of the basic subassemblies and components in developing new waterpower equipment.
It is established from a distribution of the statistical combination of failures that the performance of hydraulic turbines is characterized by a break-in period with a higher failure rate; the length of the break-in period amounts to approximately 15,000 h, after which the character of the distribution of turbine failures is rather well described by an exponential reliability law.
The greatest percentage of failures (more than 30%) occuring in the radial-axial (heads of 90–100 m) and rotary-bladed (heads of 30–40 m) hydraulic turbines consist in rotorwheel failures caused by crack development in the blades and damage to the blade seals (rotary-bladed turbines). An increase in rotor-wheel reliability requires that special design, technological, and construction measures be taken.
Analysis of the reliability characteristics obtained for the subassemlies and components demnstrated the need to increase the life of the blade seals on the rotor wheels, the shaft end seals, and the rubber cord seals of the blades in the guide apparatus; the exponential character of the failure distribution of the shaft-end seals and cord seals of the leading blades, in combination with a high failure rate, suggest inadequate improvement in the designs of these subassemblies.
Values of the readiness factor for the hydraulic turbines, which amounted to 0.9–0.99, suggest the high overall failure-free character of the equipment, which was ensured by a system of scheduled preventative-treatment repairs at the hydroelectric plants.
KeywordsHigh Failure Rate Hydroelectric Plant Reliability Characteristic Hydraulic Turbine Rotor Wheel
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